Abstract

Temperature evolution during magnetic reconnection has been spectroscopically measured for various ion species in a toroidal magnetized plasma. Measurements are made predominantly in the direction parallel to the equilibrium magnetic field. It is found that the increase in parallel ion temperature during magnetic reconnection events increases with the charge-to-mass ratio of the ion species. This trend can be understood if the heating mechanism is anisotropic, favoring heating in the perpendicular degree of freedom, with collisional relaxation of multiple ion species. The charge-to-mass ratio trend for the parallel temperature derives from collisional isotropization. This result emphasizes that collisional isotropization and energy transfer must be carefully modeled when analyzing ion heatingmeasurements and comparing to theoretical predictions.

Received 21 December 2012Accepted 26 March 2013Published online 14 May 2013

Acknowledgments:

Authors would like to thank R. M. Magee for assisting us with a collisional isotropization code. This work was supported by the US Department of Energy under cooperative agreement DE-FCO2-05ER54814 for MST and by National Science Foundation -PHY0821899.